Osteoarthritis is the steady wear and tear of your joints. This happens because the cartilage that protects your joints deteriorates over time. Cartilage is a smooth tissue that permits the bone surfaces of your joints to smoothly slide over one another. When your cartilage deteriorates, it does not regrow, so your bones rub directly against one other. The increased friction leads to inflammation, discomfort, and stiffness. Osteoarthritis can affect any joint in the body, but it is most commonly seen in the hips and knees. 

Treating Knee Osteoarthritis
Knee osteoarthritis is first treated by modifying your activities to lessen the strain on your knees and taking over-the-counter anti-inflammatory medicine (e.g., ibuprofen) to reduce inflammation. 

However, physiotherapy can help strengthen the muscles around your knees. This is because the discomfort caused by knee osteoarthritis can lower your activity levels, resulting in a vicious cycle in which your muscles weaken, putting more strain on your joints, and thus causing more pain. Physiotherapy might help stop the cycle and strengthen your knees. 

If these therapies do not work, your doctor may offer knee injections for osteoarthritis to reduce inflammation and, as a result, pain. This will allow you to do more physiotherapy activities to strengthen your knees and relieve knee osteoarthritis symptoms.  

How Does a Joint Injection Work?
Your knee joint is enclosed in a joint capsule. This capsule contains lubricating fluid, which helps your knee joint operate smoothly. However, with knee osteoarthritis, even if just one region of your knee is afflicted, inflammation can spread throughout the joint as the inflammatory cells migrate via the lubricating fluid.

Steroid injections into the knee are administered directly into the joint capsule. This permits the steroids to operate directly on the cells that are generating inflammation, preventing them from releasing chemicals that cause inflammation in your knee joint. This alleviates pain and allows you to conduct additional activities to strengthen your knee joint.

However, it is crucial to understand that your knee discomfort may worsen in the days following your injection before the steroids take effect. Your steroid joint injection will be administered in conjunction with a local anesthetic to mitigate the effects of any flare-up on your pain. If your joint injection was successful, you should begin to see results within a week.

How Long Does a Joint Injection Therapy Last?
A single steroid injection's effects endure from a few weeks to five years, depending on the individual. If your steroid injection provides long-term pain relief, you may be able to avoid knee replacement surgery. If your steroid injection provides pain relief for a few weeks, it helps to clarify that your discomfort is caused by knee osteoarthritis rather than another condition, like a trapped nerve. Steroid injections into the knee are thus employed for both therapeutic and diagnostic purposes.

How Many Joint Injections Can You Have?
The amount of steroid joint injections you can receive in your lifetime depends on the efficiency of the injections and how long their effects endure. Steroid injections become significantly less effective with each subsequent treatment.

You should avoid having too many injections in a short period of time (no more than three injections in 12 months), as this may cause harm to your knee.

The Risks of Joint Injections
Joint injections carry relatively minimal risk. However, like with every injection, there is a low chance of infection. It is also possible that your joint injection will not function.

If you receive a steroid injection into your knee joint, it is recommended that you wait four to six months before undergoing knee replacement surgery. This is because steroids can temporarily reduce your knees' immunity, and surgery increases the chance of infection, which your knee may struggle to fight off.

When Joint Injections Aren’t an Option?
If you have a prosthetic implant in your knee, such as a partial or whole knee replacement, you should avoid having a steroid injection into it. This is because prosthetic implants lack a blood supply and steroids can temporarily weaken your knee's immunity; combined, these factors increase your risk of acquiring an infection from the injection.

You should also avoid getting a joint injection if you have evidence of infection around your knee, such as a skin infection, boil, or abscess.